C02 and pH swing
 

I just started a C02 setup with a bottle. I've closely monitored it
for two days and it looks like this:

Initial parameters:
pH 7.4
KH 40 ppm
C02 calc 2.6

At the end of the first day, in the evening:
pH 6.7
KH 40 ppm
C02 calc 13.1

5:00 next morning (C02 is off at night, 1 hour after lights out)
pH 7.0

Later that day pH dropped down to 6.6 for a C02 calc of 16.5

Is a swing from 7.1 to 6.6 on a daily basis what others see? Should I
keep the C02 on all night long? How much lower will I expect the pH to
drop if I leave it on all night while the plants don't eat it?
thanks,
steve

Question: would a buffer of sodium carbonate(baking soda) help keep the
swings to a minimal??

"default" wrote in message
ups.com...
I just started a C02 setup with a bottle. I've closely monitored it
for two days and it looks like this:
snip
Is a swing from 7.1 to 6.6 on a daily basis what others see? Should I
keep the C02 on all night long? How much lower will I expect the pH to
drop if I leave it on all night while the plants don't eat it?

I think everyone's pH drops at night - anyone with real plants that is.

I haven't gotten to that stage yet so I can't verify the swings but I do
believe from the vast amounts I have been reading that (theoretically) it's
quite normal to swing overnight and during the day, even if your KH is
sufficient.

I can't answer the last part because I haven't got any injection at this
time.

No doubt, in a week or so we can both take this journey together, as next
Wednesday is the day when I start with the CO2 and I am hoping that it drops
my pH from it's current 7.8 to 6.8, or 7.0 because I'm not comfortable with
it where it is right now.

Regards,

Oz
--
My Aquatic web Blogg is at http://members.optusnet.com.au/ivan.smith

"red_foreman" wrote in message
ups.com...
Question: would a buffer of sodium carbonate(baking soda) help keep the
swings to a minimal??

I'd rather have something permanent in the water to raise the buffer. I just
get the impression that if you're going to mess with pH, KH and GH then
using "Chemicals" is laced with danger.

I think it's crushed coral that does calcium carbonate increases, but I'd
have to check.

Each to his own too I guess ;)

Oz
--
My Aquatic web Blogg is at http://members.optusnet.com.au/ivan.smith

red_foreman wrote:
Question: would a buffer of sodium carbonate(baking soda) help keep
the
swings to a minimal??


I thought so too, at first, Red. Now I understand that the buffer will
not affect the swing, but it will buffer against a crash. Using the
C02 calculator on Chucks aquariam page, (and reading his note on this
topic) you can see that the swing will be the same as C02 is added,
regardless of KH. If the KH buffer is over about 2degree, then you're
prolly not going to experience a pH crash.

steve

Just curious which test kit do you use to measure c02?
Thanks

"default" wrote in message
ups.com...
I just started a C02 setup with a bottle. I've closely monitored it
for two days and it looks like this:

Initial parameters:
pH 7.4
KH 40 ppm
C02 calc 2.6

At the end of the first day, in the evening:
pH 6.7
KH 40 ppm
C02 calc 13.1

5:00 next morning (C02 is off at night, 1 hour after lights out)
pH 7.0

Later that day pH dropped down to 6.6 for a C02 calc of 16.5

Is a swing from 7.1 to 6.6 on a daily basis what others see? Should I
keep the C02 on all night long? How much lower will I expect the pH to
drop if I leave it on all night while the plants don't eat it?
thanks,
steve

miufg wrote:
Just curious which test kit do you use to measure c02?
Thanks


Chucks Aquariam pages:

http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm

I don't actually measure the C02, it's calculated using the measured pH
and KH values. I measure those with standard, inexpensive liquid test
tube kits.

steve

"default" wrote in message
ups.com...
I just started a C02 setup with a bottle. I've closely monitored it
for two days and it looks like this:

Initial parameters:
pH 7.4
KH 40 ppm
C02 calc 2.6

At the end of the first day, in the evening:
pH 6.7
KH 40 ppm
C02 calc 13.1

5:00 next morning (C02 is off at night, 1 hour after lights out)
pH 7.0

Later that day pH dropped down to 6.6 for a C02 calc of 16.5

Is a swing from 7.1 to 6.6 on a daily basis what others see? Should I
keep the C02 on all night long? How much lower will I expect the pH to
drop if I leave it on all night while the plants don't eat it?
thanks,
steve
\


looks good to me. If you are shutting down your CO2 injection at night then
the PH is going to rise and then lower again during the day when you are
injecting. PH swings without an accompanying swing in hardness will not
cause undue harm to your fish so stay away from buffers. Personally I leave
my CO2 on 24-7 and shoot for about 25-30 PPM. In the morning my PH is
slightly lower and rises a few points during the day as the plants uptake
the co2. I don't see quite as much a swing as you do but I wouldn't be
worried about it as long as when the lights are on you are maintaining 25-30
PPM of CO2.

Rick

miufg wrote:
Just curious which test kit do you use to measure c02?
Thanks

"default" wrote in message
ups.com...
I just started a C02 setup with a bottle. I've closely monitored
it
for two days and it looks like this:

Initial parameters:
pH 7.4
KH 40 ppm
C02 calc 2.6

At the end of the first day, in the evening:
pH 6.7
KH 40 ppm
C02 calc 13.1

5:00 next morning (C02 is off at night, 1 hour after lights out)
pH 7.0

Later that day pH dropped down to 6.6 for a C02 calc of 16.5

Is a swing from 7.1 to 6.6 on a daily basis what others see?
Should I
keep the C02 on all night long? How much lower will I expect the
pH to
drop if I leave it on all night while the plants don't eat it?
thanks,
steve

Rick wrote:
Is a swing from 7.1 to 6.6 on a daily basis what others see?
Should I
keep the C02 on all night long? How much lower will I expect the
pH to
drop if I leave it on all night while the plants don't eat it?
thanks,
steve
\


looks good to me. If you are shutting down your CO2 injection at
night then
the PH is going to rise and then lower again during the day when you
are
injecting. PH swings without an accompanying swing in hardness will
not
cause undue harm to your fish so stay away from buffers. Personally I
leave
my CO2 on 24-7 and shoot for about 25-30 PPM. In the morning my PH is
slightly lower and rises a few points during the day as the plants
uptake
the co2. I don't see quite as much a swing as you do but I wouldn't
be
worried about it as long as when the lights are on you are
maintaining 25-30
PPM of CO2.

Rick

Thanks for the input, Rick. I'll get a chance this weekend to monitor
it more closely. I have the valves set now so it produces a constant
bubble rate (80bbm) throughout the day and at startup. I'm going to
leave it on all night too, and measure that before lights on to see how
far it drops overnight. If the swing is much milder with it left on
(like .2 or so in your case) I'll chose between a larger swing and
saving about 1/3 the gas.

thanks again,
steve

Hi all,

I was advised that ideally (and I know that I can't really get that part
right) your PH should be about 7.2 in the morning - before CO2 and at night
(just before CO2 is turned off) should sit at around 6.8. This is
maintained by keeping your KH at 2-3 degrees. Of course the amount of
plants you have absorbing O2 overnight makes a difference as well as
everything else.

Hope this helps.

Justin
"red_foreman" wrote in message
ups.com...
Question: would a buffer of sodium carbonate(baking soda) help keep the
swings to a minimal??

red_foreman wrote:
Question: would a buffer of sodium carbonate(baking soda) help keep the
swings to a minimal??

I used to add a bit of baking soda to my CO2 injected planted tank and
it worked great. Baking soda sets up a bit of extra carbonate buffering
which lessens the pH swings. I think I added a total of about a
teaspoon to my 29 gallon tank, over a few days. If you add too much, it
will raise the overall pH of the tank so keep monitoring it and add very
gradually. Like any salt, you will have to add more with water changes.

Elaine